[Columbus] Columbus Digest, Vol 128, Issue 3

[Aleksandr Zaichenko]

Dear Hans,

Yes. Correct. It is the MR-CISD program. Excitations in the virtual space
are 0, moreover all virtual orbitals as well as lower are frozen.

The problem size from cidrtls is:

total: 38760

and it seems correct. The growth of the memory demand occurs in the
diagint file
up to 1.2 Tb and calculation falls with SIGSEGV.

It should not happen with the CI-problem of that dimension including only
one root with SO, as I know. I can share listings, if you will need it.

Best,
Aleksandr



On Mon, Mar 24, 2025 at 6:46 PM <columbus-request at lists.osc.edu> wrote:

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>    1. CASCI extraordinary memory demand (Aleksandr Zaichenko)
>    2. Re: CASCI extraordinary memory demand (Hans Lischka)
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> Message: 1
> Date: Mon, 24 Mar 2025 15:36:14 -0400
> From: Aleksandr Zaichenko <alex.zai90 at gmail.com>
> To: columbus at lists.osc.edu
> Subject: [Columbus] CASCI extraordinary memory demand
> Message-ID:
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> BKkgUz6Qvc9A at mail.gmail.com>
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> Dear Columbus Team,
>
> I have a question about an ressources requirement issue with the CI module
> for the CASCI calculation. A calculation with active space CAS(6,20)
> without any external excitations (all lower orbitals are frozen, all higher
> orbitals are removed) contains 38760 CI-vectors (as should be) and I should
> get an CI-only solution for only one first root. Most QC programs do this
> calculation without any problem, but the Columbus CI module requires more
> than 1 Tb memory for that and it seems very demanding. Why is it so? Do I
> understand correctly, that the program tries to construct a full-CI problem
> for all of the 38760 roots despite 1 root being required?
>
> Best,
> Aleksandr
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> Message: 2
> Date: Mon, 24 Mar 2025 17:45:30 -0500
> From: Hans Lischka <hans.lischka at univie.ac.at>
> To: columbus at lists.osc.edu
> Subject: Re: [Columbus] CASCI extraordinary memory demand
> Message-ID: <bc527a53-1a8d-4bea-b08a-30e2d1f800d1 at univie.ac.at>
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>
> Hi Aleksandr,
> I am not sure what kind of calculation you really did. The CI module is
> meant to do a MR-CISD calculation. I assume you took the CAS(6,20) as
> reference? How did you proceed further? The CI program will want to
> create all SD excitation from the 38760 configurations. Did you opt for
> that? This would explaining the 1TB of memory required. Look into the
> cidrtls file. There you will see the CI dimension. If you want the CASCI
> calculation you should input zero excitations (into the virtual space).
> Please let e know what you did.
> Best regards, Hans
>
> On 3/24/2025 2:36 PM, Aleksandr Zaichenko via Columbus wrote:
> > Dear Columbus Team, I have a question about an ressources requirement
> > issue with the CI module for the CASCI calculation. A calculation with
> > active space CAS(6,20) without any external excitations (all lower
> > orbitals are frozen, all higher orbitals
> > Dear Columbus Team,
> >
> > I have a question about an ressources requirement issue with the CI
> > module for the CASCI calculation. A calculation with active space
> > CAS(6,20) without any external excitations (all lower orbitals are
> > frozen, all higher orbitals are removed) contains 38760 CI-vectors (as
> > should be) and I should get an CI-only solution for only one first
> > root. Most QC programs do this calculation without any problem, but
> > the Columbus CI module requires more than 1 Tb memory for that and it
> > seems very demanding. Why is it so? Do I understand correctly, that
> > the program tries to construct a full-CI problem for all of the 38760
> > roots despite 1 root being required?
> >
> > Best,
> > Aleksandr
> >
> > _______________________________________________
> > Columbus mailing list
> > Columbus at lists.osc.edu
> > https://lists.osu.edu/mailman/listinfo/columbus 
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